Fusible link



Oct. 24, 1967 B. J. MACARTNEY FUSIBLE LINK Filed Sept. 13, 1965 INVENTOR glPI/Cf JM4a4Rr/ws 7 MAM/41 ATTORNEY United States Patent Ofi Fice 3,348,617 Patented Got. 24, 1967 3,348,617 FUSIBLE LINK Bruce J. Macartney, Chatham, N.J., assignor to The Fyr-Fyter Company, New York, N.Y. Filed Sept. 13, 1965, Ser. No. 487,008 1 Claim. (Cl. 169-42) The present invention relates to the art of fire protection and more particularly to a fusible link suitable for releasing a load responsive to a temperature rise.

The fusible link may be incorporated into the release operating mechanism for fire doors and windows, or to release the control for any sort of device such as a fire detector, fire alarm, fire extinguishment apparatus, or the like, in which the control for the device is to be operated upon the attainment of a predetermined temperature rise.

The present invention aims to provide an improved fusible link which is of tamper-free construction and dependable in operation even after many years of service.

In accordance with the invention this is accomplished by a fusible link in which a pair of tension members are releasably held together with a thermally responsive element by clamping means.

An object of the invention is to provide a fusible link which is simple and economical in manufacture, accurate in operation, and durable in use.

Other objects and advantages of the invention will be apparent from the following description and from the accompanying drawings which show, by way of example, an embodiment of the invention.

In the drawings:

FIGURE 1 is a schematic drawing showing a fire door carried by an inclined track and held from closing by a weight connected to a cable through a fusible link constructed in accordance with the invention.

FIGURE 2 is a top view of the fusible link.

FIGURE 3 is a sectional view taken along the line 3-3 of FIGURE 2.

FIGURE 4 is an end view of the fusible link shown in FIGURE 2.

Referring to the drawings there is shown in FIGURE 1 a passageway adapted to be closed ofl? by a fire door 11 carried by a pair of hangers 12 on an inclined track 14. The door 11 is restrained from closing by a weight 15 connected to a cable 16 which passes over a pulley 17 and is attached to the door 11 by a fusible link 20.

The fusible link 20 includes a pair of tension members 21 and 22 having, respectively, enlarged ends 24 and 25' provided with openings 26 and 27. At their adjacent ends the tension members 21 and 22 are provided with nesting deformations 29 and 30 formed of a projection on one side and a depression on the opposite side. A thermally releasable element 31 is engaged against the nesting deformations 29 and 30, the fusible link assembly being held together by a clamping member 32 which has an inwardly directed nesting deformation 34.

The fusible element 31 includes a generally cup-shaped base member 35 having a flattened end surface 36. A mass of fusible material 37 is positioned within the cupshaped base member 35. Abutted against the fusible material 37 is a piston member 39 which is sealed in position by inwardly turned edges 40 of the open end of the cup shaped member 35. The piston member 39 is provided with a recess 41 adapted to receive the projection 30 of the tension member 22.

The fusible material 37 is well known in the art and may be made of metal alloys or chemical materials normally solid and liquefiable at a desired temperature, for example, at 160 degrees F. Such materials are not limited to but may include solder, dichlorobenzene, benzyl disulfide, or cobalt nitrate. The fusible material 37 is confined in the cavity of the base member 35 and thus is not subjected to shearing stress. Edges 42 of the piston member 39 are spaced from the inner surface of the side walls of the base member 35 so as to provide a clearance of approximately .05 to .08 inch in order that the fusible material 37 may pass through this space when fused. The construction of the fusible element 31 is well known in the art.

The clamping member 32 may be made from a short length of square tubing or fabricated in any other conventional manner. In assembling the fusible link 20 the fusible element 31 and the tension members 21 and 22 are placed in position within the clamping member 32 with the deformations 29 and 30 in nesting arrangement with the recess 41. The assembly is then locked together by making the nesting deformation 34 as by the use of a press.

It will be noted that a tension force applied to the outer ends of the members 21 and 22 is transformed to a compressive force through the piston member 39 to the fusible material 37. Upon the attainment of a predetermined temperature the fusible material melts and the piston member 39 is forced therein, thereby releasing the tension members 21 and 22. In the event the fusible link is connected into a door restraining mechanism as shown in FIGURE 1, the weight 15 is released so that the door 11 slides down the track 14 to close off the passageway 10.

From the preceding description it will be seen that the present invention provides a fusible link of compact construction. In a commercial embodiment the clamping member 32 is about inch square and inch in length and the overall length of the tension members may be about 2 inches.

While the invention has been described and illustrated with reference to a specific embodiment thereof, it will be understood that other embodiments may be resorted to without departing from the invention. Therefore, the form of the invention set out above should be considered as illustrative and not as limiting the scope of the following claim.

I claim:

A load supporting fusible link comprising a pair of fiat tension members positioned with the adjacent end of one tension member overlapping the adjacent end of the other tension member, means located at the outer ends of said tension members for attachment thereof to a load, a thermally responsive element including a cup shaped container receiving a fusible material, a piston member abutting the surface of the fusible material and closing the opening of the cup shaped member, the cup shaped member having a fiat base, the piston member having a recessed end, and a clamping member of generally square cross sectional shape encircling said thermally responsive element and said overlapping ends of said tension members, the adjacent surfaces of said clamping member and said overlapping tension members deformed into said recessed end of said thermally responsive element.

References Cited UNITED STATES PATENTS 277,478 5/1883 Grinnell 169-42 911,162 2/1909 Rockwood 16942 1,209,574 12/1916 Grimes 169-42 1,953,582 4/1934 Belknap 169-42 3,161,236 12/1964 Macartney 169--39 EVERETT W. KIRBY, Primary Examiner. 

